What is the accuracy difference between Fixed and Float RTK?

Fixed RTK typically delivers ±8 mm horizontal and ±15 mm vertical accuracy. Float RTK carries ±300–1000 mm of positioning error depending on baseline length and atmospheric conditions.

Why does my RTK show Fixed but coordinates are still wrong?

Common causes are a datum mismatch (wrong coordinate system), an incorrect geoid model applied to elevation, or an antenna height entry error.

How do I know if multipath is affecting my survey?

Multipath typically shows as unstable repeated measurements — the same physical point measured three times gives results differing by 20–50 mm rather than the expected ±8 mm.

Can I survey during ionospheric storms?

RTK accuracy degrades during geomagnetic storms (Kp index above 5). For precision engineering or cadastral surveys, postpone sessions until the Kp index drops below 3.

What is the maximum reliable CORS baseline for centimetre accuracy?

Most CORS networks guarantee ±10–20 mm horizontal accuracy within 50 km of the nearest reference station. Beyond 70 km, deploy a self‑deployed base station within 15 km of the survey area.

APEKS FAQ | How to Do Static GNSS Surveying Step by Step

2025-07-01

How to Do Static GNSS Surveying Step by Step

Today we're diving into an important GNSS technique: static measurement. This method is commonly used for establishing control points in surveying, ensuring precise coordinates for RTK, total station work, or geodetic networks.

Let's walk through the steps — from site prep to data recording — to help you get accurate results in the field.

📝 Before You Start: Key Reminders

Before heading into the field, here are a few things to keep in mind:

For RTK control points: Place the points evenly around the area you want to measure, not just in one corner.
For total station or theodolite use: Keep the points within line of sight and not too far apart.
Always check the site in advance — avoid locations with large obstructions, and make sure markers are visible and protected from damage or disturbance.

📍Step 1: Set Up the Equipment

Let's watch our engineer set up the gear:

Mount the tripod firmly over the control point.
Use optical or laser centering to align the instrument precisely over the mark.
Level the receiver by centering the bubble in the tubular level.
Once it's leveled, measure the slant height (from the mark to the antenna phase center).
- Take this measurement from three different directions.
- Average the results and record the final height.

🔧 Step 2: Configure the Static Survey

Now let's configure the GNSS receiver for static data collection:

On the receiver screen, select Static mode.
Enter the point name — for example, we'll use "AREKS".
Set the cut-off angle — a common setting is 10 degrees.
Choose the logging interval, such as 1 Hz.
Set the observation time depending on your survey needs (e.g. 30 minutes or 2 hours).
Under "Execute After Completion", select Shut Down if you want the receiver to turn off automatically after recording.
Set Antenna Measuring Type to Slant Height to Altimetry.
Enter the Antenna Measure Height — use the average you measured earlier.

Once everything is correctly set — press Start Recording.

⏱️ Tips for Using Multiple Receivers

If you're using three GNSS receivers for static measurements:

You can set up one receiver first, power it off, then prepare the others.
Once all receivers are ready, turn them on at the same time — this syncs the observation window.
Alternatively, you can turn them on one by one — but the recording time starts from the last one powered on.

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